The causes of masturbation are different at the different periods of the individual’s life. In early childhood, a neuropathic predisposition, eczema, pruritus, phimosis, accumulation of smegma, early retiring and late rising, spicy food and exciting drinks, absolute ignorance of sex and seduction by vicious servants will be the principal causes for autoeroticism. During the time of school-life seduction is the cause par excellence of masturbation. Self-abuse is widely spread in schools. No institution is free from it. In nearly every school there is at least one lecherous boy who is apt to be peculiarly fascinating to his fellows and who will promulgate the habit. In some schools the evil reaches a wide extension. The tradition of the school and the material of the pupils is of great influence. Particularly dangerous, as hatcheries and divulgers of the evil, are those institutions in which numerous pupils are present who have passed the normal age by several years. They come, as a rule, from the country to enter the advanced classes. The time of puberty is another period favorable for acquiring the habit of masturbation. When the genital centres are fully developed, the individual gets a conscious realization of its sexual power, and the psychological reactions of animal passion manifest themselves in the desire to cause a relaxation and a discharge of the nervous tension and of the physical genital congestion. The opportunity for the natural discharge being connected with great difficulties, especially for the girl, there is danger that the child will resort to masturbation to be relieved from the nervous tension and the material congestion. During the post-puberty period which in men reaches to the twenty-fourth year and in women to the twentieth year of age, the extension of the masturbatic practices gradually decreases, and by the time manhood and womanhood have been reached, masturbation has almost entirely disappeared. Its presence after this period may be considered pathological except it is practised out of necessity as in the following case: Mr. A., thirty-five years old, married twelve years, father of two healthy children, was always well. Three years ago he left his native country and came to America. Faute de mieux, he began to practise autoeroticism inordinately and continued in this practice until he became a nervous wreck, showing all the symptoms of neurasthenia besides impotence and nocturnal emissions. In this case the patient became perfectly well after his wife arrived in this country.